A number of types of jet mill are known in which particulate material is entrained in a jet of gas and reduced in size either by being caused to impinge upon a target or by collision with other particles. In such a jet mill the energy of the gas, typically steam, used in the jet is significant and it is therefore important to use this energy as efficiently as possible.
It is an object of this invention to provide a method of milling particulate material in a more energy efficient manner than has been possible hitherto.